• 정보처리학회논문지A
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• 제15A권4호
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• pp.239-242
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• 2008

외부 메모리 계산 모델에서 스트링의 최대서픽스를 찾는 문제를 고려한다. 외부메모리 모델에서는 디스크와 내부메모리 사이의 디스크 입출력 횟수를 줄이는 알고리즘을 설계하는 것이 중요 사항이다. 길이가 N인 스트링은 N개의 서픽스를 가지는데, 이중에서 사전 순서에 따라 가장 큰 것을 최대 서픽스라 부른다. 최대서픽스를 구하는 것은 여러 스트링 문제를 해결하는 데 중요한 역할을 한다. 본 논문에서는 길이가 N인 스트링의 최대 서픽스를 구하는 외부메모리 알고리즘을 제시한다. 이 알고리즘은 네 개의 내부 메모리 블록을 사용하고 최대 4(N/L)번의 디스크 입출력을 한다. 여기서 L은 블록의 크기이다.

• 방송공학회논문지
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• 제24권6호
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• pp.1096-1112
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• 2019

현재 360 VR 이미지를 만들어주는 카메라들은 상당히 고가이기에 사람들이 손쉽게 사용할 순 없는 상황이다. 이를 해결하기 위해 휴대 전화의 카메라를 이용해 100여 장의 사진을 360° 촬영을 한 후 Image stitching으로 360 VR 영상을 얻고자 한다. 기존의 장비는 한 번에 360℃ 촬영으로 VR 영상을 만들어내는 반면 휴대 전화를 이용하여 촬영할 경우 영상마다 시차가 생기게 된다. 이로 인해 움직이는 물체가 있는 경우 물체가 여러 장의 영상에서 나타나는 원하지 않는 상황이 생기게 되고 Seam이 물체를 관통하여 부자연스러운 결과 영상을 얻게 된다. 본 논문에서는 시각적으로 두드러지는 물체를 판별할 수 있는 Saliency map을 이용한 Seam finder 알고리즘을 통해 개선된 결과 영상을 얻을 수 있음을 확인했다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4503-4508
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• 2010

전파 신호원의 방위를 정확하게 찾는 기술은 전자전에서 매우 중요하다. 전파 신호원의 방위를 찾기 위한 방위탐지 기술이 많이 연구되고 있으며, 최근에는 신호 도착시간차이(TDOA)를 이용하는 방위탐지 연구가 많이 진행되고 있다. TDOA 기술은 두 개의 배열 안테나에 도달하는 신호의 도착시간차이를 이용하여 신호원의 방위을 도출하는 방식이며, 방위탐지 오차는 배열 안테나의 기준선 길이와 시간측정 분해능과 관련이 있다. 본 논문에서는 10m*10m의 제한된 공간에서 안테나 배치 방법과 이에 대한 방위탐지 오차를 분석하여 최적 안테나 배치 방법을 제시하였다.

• 한국기록관리학회지
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• 제2권2호
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• pp.93-106
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• 2002

EAD(Encoded Archival Description)는 기록자료의 기술도구인 "finding aid"를 전자형태로 구축하여 온라인 상에 자료의 내용과 구조를 제공하기 위하여 개발되었다. Online Archive of California(OAC) 프로젝트는 EAD를 이용하여 기록자료를 통합데이터베이스로 구축함으로 기록자료를 언제 어디서나 검색할 수 있도록 하는 전자자료관 실현에 크게 기여하고 있다. 이 글은 OAC 프로젝트와 EAD의 내용, 구조, 태그, 예 등을 살펴보고, 기록관리학 분야에서의 기여와 한국적 EAD의 필요성에 대해 토론한다.

• 한국컴퓨터정보학회논문지
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• 제24권7호
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• pp.125-133
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• 2019

Because military weapons systems for special purposes are small and complex, they are not easy to maintain. Therefore, it is very important to maintain combat strength through quick maintenance in the event of a breakdown. In particular, naval ships are complex weapon systems equipped with various equipment, so other equipment must be considered for maintenance in the event of equipment failure, so that skilled maintenance personnel have a great influence on rapid maintenance. Therefore, in this paper, we analyzed maintenance data of defense equipment maintenance information system through text mining and social network analysis(SNA), and tried to identify the naval ship maintenance expertise. The defense equipment maintenance information system is a system that manages military equipment efficiently. In this study, the data(2,538cases) of some naval ship maintenance teams were analyzed. In detail, we examined the contents of main maintenance and maintenance personnel through text mining(word cloud, word network). Next, social network analysis(collaboration analysis, centrality analysis) was used to confirm the collaboration relationship between maintenance personnel and maintenance expertise. Finally, we compare the results of text mining and social network analysis(SNA) to find out appropriate methods for finding and finding naval ship maintenance expertise.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.685-695
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• 2021

This study explores the impact of stochastic volatility in option pricing. To be more specific, we compare the option pricing performance between stochastic volatility option pricing model, namely, Heston option pricing model and standard Black-Scholes option pricing. Our finding, based on the market price of SET50 index option between May 2011 and September 2020, demonstrates stochastic volatility of underlying asset return for all level of moneyness. We find that both deep in the money and deep out of the money option exhibit higher volatility comparing with out of the money, at the money, and in the money option. Hence, our finding confirms the existence of volatility smile in Thai option markets. Further, based on calibration technique, the Heston option pricing model generates smaller pricing error for all level of moneyness and time to expiration than standard Black-Scholes option pricing model, though both Heston and Black-Scholes generate large pricing error for deep-in-the-money option and option that is far from expiration. Moreover, Heston option pricing model demonstrates a better pricing accuracy for call option than put option for all level and time to expiration. In sum, our finding supports the outperformance of the Heston option pricing model over standard Black-Scholes option pricing model.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.596-604
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• 2020

Previous studies on pipe auto-routing algorithms generally used such algorithms as A*, Dijkstra, Genetic Algorithm, Particle Swarm Optimization, and Ant Colony Optimization, to satisfy the relevant constraints of its own field and improve the output quality. On the other hand, this study aimed to significantly improve path-finding speed by applying the Jump Point Search (JPS) algorithm, which requires lower search cost than the abovementioned algorithms, for pipe routing. The existing JPS, however, is limited to two-dimensional spaces and can only find the shortest path. Thus, it requires several improvements to be applied to pipe routing. Pipe routing is performed in a three-dimensional space, and the path of piping must be parallel to the axis to minimize its interference with other facilities. In addition, the number of elbows must be reduced to the maximum from an economic perspective, and preferred spaces in the path must also be included. The existing JPS was improved for the pipe routing problem such that it can consider the above-mentioned problem. The fast path-finding speed of the proposed algorithm was verified by comparing it with the conventional A* algorithm in terms of resolution.

• Imaging Science in Dentistry
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• 제52권3호
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• pp.319-326
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• 2022

This report presents the case of a 5-year-old boy with a hard swelling on the right side of the mandible body. An important point of this case is that the primary imaging finding was fine spicules in the inferior border of the mandible on panoramic radiography without significant changes in bone density. Cone-beam computed tomography views revealed a lytic lesion on the lingual side of the right mandibular body with the destruction of the lingual cortex and periosteal reaction from the midline to the first molar area. Careful attention to this radiographic finding in the primary stage in the absence of other significant imaging findings, particularly in children, could result in the early diagnosis of desmoplastic fibroma. Therefore, a better prognosis can be expected following early surgical treatment.

• 천문학회보
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• 제46권2호
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• pp.42.1-42.1
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• 2021

Galaxy/Halo finding based on the friends-of-friend (FoF) algorithm has been widely adopted for its simplicity and expandability to the phase-space. However, cosmological simulations have been progressively bigger in size and more accurate in resolutions, resulting in that galaxy/halo finding gets computationally expensive more and more. In fact, we confirm this issue through our exercise of applying the 6-dimensional (6D) FoF galaxy finder code, VELOCIraptor (Elahi et al.2019) on the NewHorizon simulation (Dubois et al. 2021), in which typical galaxies with about 1e11 M_sun (10⁷ particles) are identified with very low speed (longer than a day). We have applied several improvements to the original VELOCIraptor code that solve the low-performance problem of galaxy finding on a simulation with high resolutions. Our modifications find the exact same FoF group and can be readily applied to any tree-based FoF code, achieving a 2700 (12) times speedup in the 3D (6D) FoF search compared to the original execution. We applied the updated version of VELOCIraptor on the entire NewHorizon simulation (834 snapshots) and identified its galaxies and halos. We present several quick comparisons of galaxy properties with those with GALAXYMaker data.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.92-99
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• 2024

To minimize the cumulative radiation dose, various path-finding approaches for single agent have been proposed. However, for emergence situations such as nuclear power plant accident, these methods cannot be effectively utilized for evacuating a large number of workers because no multi-agent method is valid to conduct the mission. In this study, a novel algorithm for solving the multi-agent path-finding problem is proposed using the conflict-based search approach and the objective function redefined in terms of the cumulative radiation dose. The proposed method can find multi paths that all agents arrive at the destinations with reducing the overall radiation dose. To verify the proposed method, three problems were defined. In the single-agent problem, the objective function proposed in this study reduces the cumulative dose by 82% compared with that of the shortest distance algorithm in experiment environment of this study. It was also verified in the two multi-agent problems that multi paths with minimized the overall radiation dose, in which all agents can reach the destination without collision, can be found. The method proposed in this study will contribute to establishing evacuation plans for improving the safety of workers in radiation-related facilities.